Environmental Barrier Coating Densification via Precursor
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Solution Overview
Problem
Conventional environmental barrier coatings for ceramic matrix composite (CMC) parts in turbomachines suffer from defects such as porosity and cracking, which reduce their hermeticity and effectiveness in preventing corrosion and oxidation, especially under high-temperature and corrosive conditions, and existing methods for improving sealing are inefficient in achieving homogeneous distribution of densification agents.
Innovation Solution
A method involving coating rare earth silicate powder with a precursor of a densification agent, followed by thermal spraying and heat treatment to form a crystallized and densified environmental barrier, which ensures homogeneous distribution and controlled dosage of the densification agent, reducing the mass content required and enhancing the coating's hermeticity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If thermal spraying is used to prepare EBC, then the coating can be applied to CMC parts, but the coating contains porosity and cracks that reduce hermeticity
Solution Approach 1:
The densification agent is incorporated into the powder before thermal spraying, performing the densification action in advance during the coating formation process. This preliminary incorporation allows the densification to occur uniformly throughout the coating structure, addressing porosity and cracking issues that would otherwise require separate post-treatment steps.
Solution Approach 2:
The invention changes the physical and chemical parameters of the coating by incorporating a densification agent that undergoes phase transformation during thermal spraying. The agent modifies the coating's microstructure by filling voids and sealing cracks, transforming the porous sprayed coating into a denser, more hermetic barrier through controlled parameter changes during the spraying process.
2Reliability
If sintering agents or healing agents are added to improve sealing, then hermeticity can be enhanced, but homogeneous distribution of the agents is difficult to achieve
Solution Approach 1:
The densification agent is segmented into fine particles that are uniformly distributed throughout the coating powder mixture. This segmentation allows the agent to be evenly dispersed at the microscale, ensuring consistent sealing performance throughout the entire coating without aggregation or localized concentration variations.
Solution Approach 2:
The invention creates a composite powder material combining the base coating material with the densification agent in specific proportions. This composite approach ensures homogeneous distribution of the sealing agent within the coating matrix, achieving uniform sealing properties throughout the EBC while maintaining the structural integrity of the underlying CMC.
3Reliability
If densification agent is added to the powder mixture, then hermeticity improves, but the mass content of densification agent increases
Solution Approach 1:
The densification agent is applied with local quality by concentrating it specifically at defect sites such as porosity and crack regions within the coating. This localized placement ensures that the agent acts precisely where needed to seal defects, maximizing hermeticity improvement while minimizing the overall quantity of densification agent required in the coating formulation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method produces a more effective environmental barrier with improved hermeticity, reducing silica volatilization and enhancing the durability of CMC parts by achieving a homogeneous and finely dispersed distribution of densification agents, thereby extending the service life of CMCs in turbomachines.
Implementation Method 1
During thermal spraying, the precursor of the densification agent will react to form the densification agent on the rare earth silicate powder
Implementation Method 2
thermally treating the environmental barrier in order to crystallize and densify the environmental barrier
Implementation Method 3
thermally treating the environmental barrier in order to crystallize and densify the environmental barrier
Implementation Method 4
thermally spraying the coated powder onto a substrate in order to obtain an at least partially amorphous environmental barrier on the substrate
Data Source
AI summary
A method for manufacturing an environmental barrier comprising the steps of coating a rare earth silicate powder with a precursor of a densification agent in order to form a rare earth silicate powder coated with the precursor of the densification agent, thermally spraying the coated powder onto a substrate in order to obtain an at least partially amorphous environmental barrier on the substrate and thermally treating the environmental barrier in order to crystallize and densify the environmental barrier.